+
Departure Time
+
In some cases, the rMove app may have detected the start of a trip
+after its true start time, which can yield invalid or extreme values for
+trip duration and speed. In these cases, the fields depart_date,
+depart_hour, and depart_minute were adjusted for “late pickup”
+conditions using the following approach:
+
+- Departure time was imputed using the median speed between all
+locations along the trip, excluding the origin point, and the distance
+between the origin and the next point on the trip. For trips with fewer
+than three recorded locations, imputed departure time is set three
+minutes earlier than the original departure time to compensate for
+rMove’s 3-5-minute ping interval. Note that some trips that are the
+result of split loop trips may only have three or fewer points but will
+use the imputed depart time from before the loop trip was split and thus
+may not be included in this rule.
+- If the imputed departure time overlaps with the previous trip’s
+arrival time, the previous trip’s arrival time was instead used as the
+departure time. Regardless of the number of locations along a trip, if
+the imputed departure time was later than the initially reported
+departure time, the imputed departure time is set to the original
+departure time. User-added trips as well as long distance passenger mode
+trips are also set to the original departure time, as user-added trips
+are not subject to “late pickup” conditions, and long-distance passenger
+modes are often plane trips where all collected traces contain speed
+information from other modes and thus are less reliable (as rMove cannot
+collect locations when a phone is in “airplane mode”).
+
+
Duration and speed are calculated based on the imputed departure
+time.
+
Purpose
+
Respondents report the purpose of the trip destination in each trip
+survey. The origin purpose is derived from the destination purpose of
+the previous trip, except for the first trip in the travel period or
+where an rMove trip occurs after a trip survey whose survey is
+incomplete due to non-response. For the first trip in the travel period,
+the origin purpose can be inferred from “begin_day” in the day
+table.
+
When purpose was not asked because an analyst split a user-reported
+trip during data cleaning (creating a new destination along a trip),
+purpose values are derived where possible based on proximity (within 150
+meters) to estimated home, work, or school locations. If the location is
+not proximate to home, work, or school locations, the purpose is set to
+“other.”
+
The purpose category variables (o_purpose_category,
+d_purpose_category) contain aggregated purpose values based on the type
+of purpose at the origin/destination of each trip. Dataset users are
+welcome to perform their own recoding of the purpose categories as
+well.
+
Trip purposes have been imputed in cases where a purpose reported by
+the user is assumed to be inaccurate based on information about that
+person’s reported habitual locations and other trips (primarily to home,
+work, and school locations). The trip purpose imputation approach was
+applied to all rMove trips in person-days with at least 1 complete trip
+and no more than 10 incomplete trips. (“Incomplete” trips are trips for
+which the respondent did not answer the trip-specific survey questions
+about purpose, mode, etc. for the given trip.)
+
The approach was to apply various “tests” in logical sequence to
+trips for which the stated purpose is not consistent with the location
+type based on the reported habitual locations. In general terms, the
+tests were designed to:
+
+- Check the respondent’s reported destination purpose when it
+conflicts with the destination location type. (The details of the tests
+depend on the trip purpose, with different criteria used for change-mode
+trips, escort trips, linked transit trips, trips with home destinations
+but other reported purposes, etc.)
+- Identify cases where respondents swapped the order of two or more
+trips when reporting their details.
+- Identify cases where respondents may have omitted a trip and shifted
+remaining reported trip details by one trip when reporting the rest of
+their trips.
+- Fill in missing data by sampling destination purposes from other
+trips made to the same locations, either by the same respondent or by
+other respondents.
+
+